I do not want to comment on the wheelchairs, but, in regard to the locker and the parking increases, a pretty basic rule of econ/tax policy applies. Subsidize behaviors you want to encourage, tax behaviors you want to discourage.
Disney runs buses, monorails, and boats to their parks. They would prefer customers use these expensive modes of transit rather than drive their cars. There is no reason for them to waste money on public and private transit infrastructure. They are not a municipality. Also, the high parking fee brings the price of staying off-site and on-site closer to equilibrium. Without seeing any numbers, it seems reasonable to intuit that a certain population on the margin will choose to move to staying on property. As long as the value of those who choose to stay on-site because of extra costs is greater than the value lost from people who are dissuaded, it is a good business decision. Plus, it jives with their environmental initiative.
On lockers, Disney likely faces very little overhead for the lockers. They are cheap to maintain/replace and generate large returns when used. Someone's joke about Windex, however, is not far off. What is not seen is the added cost of having lockers to things like security. If people need space to store their stuff they bring in the park, they are likely bringing too much stuff. Excess stuff slows down security checks and makes it easier for weapons, liquor, etc to slip through. In the very busiest times, even a two second delay for each person moving through security could cripple service flow for the entire day (see queing models).
While some see this as nickel and diming, I can see the business prospective. If people freak out about reductions in service (ie ripping out the lockers) then another approach is to price them out of a behavior. Have the customer ask if it is worth $9 to them to be able to bring extra coats, ubrellas, etc rather than the company take away the storage option. Some people will decide to pay because money is no object or they see the value while others will say let's risk it and if we get too cold I will run to the car or just buy a new sweatshirt.
You make these types of decisions all the time in the world. Whether you buy off brand poptarts or brand name catchup, you decided if a service was worth the price. Making these choices in the World are no different.... And if you are honest with yourself, the "losing the magic" arguement does not work here either, unless the lockers at DHS actually led to Narnia or Fraggle Rock or something.